Dry reagent based water analyzer

Abstract

The invention provides devices, methods, and compositions for dry chemical reagents to measure calcium, magnesium (total hardness), and other analytes in water using colorimetric devices. The measurement may be a one-step procedure without the need of dilution and multi-step preparation, so that it can be easily employed by untrained personnel. The chemical reagents may include dyes, buffer reagents, masking reagents, competing ligands, and other chemicals such as fillers. The chemical reagents may be grinded together as a homogenous fine powder, equally dispensed into small containers for each test or dried as film or solid using the means of air, low heat or vacuum. The composition may be easily dissolved into water samples and stable for long term storage. The methods may be able to distinguish between similar materials such as magnesium and calcium with the same one reagent or from other interfering species in water samples

1 . A method of testing for the presence of an analyte in a liquid sample comprising the steps of:
 pre-determining the spectrographic relationship between a given amount of dry reagent and varying concentrations of an analyte when combined in a given amount of liquid carrier,   adding a sample of the liquid carrier to a container bearing the given amount of dry reagent, and   spectrometrically measuring the amount of analyte in the sample.   
     
     
         2 . The method of  claim 1  in which the analyte is magnesium and or calcium. 
     
     
         3 . The method of  claim 1  in which the liquid carrier is water. 
     
     
         4 . The method of  claim 2  in which the dry reagent will indicate a positive result for both calcium and magnesium, the method further comprising the step of adding a masking compound to sufficiently inhibit interactions between calcium and the dry reagent so a measurement of only magnesium can be obtained. 
     
     
         5 . The method of  claim 2  in which the dry reagent will indicate a positive result for both calcium and magnesium, the method further comprising the step of adding a masking compound to sufficiently inhibit interactions between magnesium and the dry reagent so a measurement of only calcium can be obtained. 
     
     
         6 . The method of  claim 2  in which the type of spectrometric measurement used is colorimetry. 
     
     
         7 . The method of  claim 2  in which the amount of analyte in the sample relative to the amount of dry reagent is beyond a threshold for maximum possible accurate measurement, the method further comprising contacting the sample with a ligand composition that reduces the amount of magnesium and calcium free to interact in proportional amounts so that an accurate measurement of calcium and magnesium can be obtained. 
     
     
         8 . The method of  claim 1  further comprising the step of vacuum sealing the container and storing it for a period of time beyond which a liquid form version of the reagent would no longer be effective and conducting the measurement after the period of time has elapsed. 
     
     
         9 . The method of  claim 1  in which the dry reagent comprises a dye, a chelating agent, and buffering agents, wherein the chelating agent is selected from a group consisting of hydroxy carboxylic acid salt and amino carboxylic acid salts, citric acid, phosphonobutane tricarboxylic acid, EDTA, and nitrilotriacetic acid, and any combination thereof; and the buffering agents can adjust pH in a range of from about 8 to about 10. 
     
     
         10 . The composition according to the  claim 9  wherein the dye is orthocresolphthalein complex one, OCPC and any combination thereof. 
     
     
         11 . The method of  claim 1  in which the container is one of a series of linked containers, each container containing a dry reagent suitable for measuring the amount of a different analyte in a liquid. 
     
     
         12 . The method of  claim 1  in which the dry reagent is in the form of a powder. 
     
     
         13 . The method of  claim 7  in which but for the ligand composition the measurement would result in an absorbance of 3 AU or greater.